Tip: The dogs in question might be in need of medical care, and could be homeless.

According to the Purina Pet Institute, they're all over Cincinnati.

Cincinnati ranks 45th out of 50 in a recent survey gauging pet-healthy cities, according to the institute.

Purina evaluated 30 criteria, such as a city's air quality, veterinarian-to-pet ratio, percentage of neutered pets, animal legislation and number of shelters.

And, of course, pet obesity.

Dr. Darrell Gitz of Oakley Square Animal Hospital doesn't know of any hard evidence that Cincinnati's dogs are fatter than those of other cities. But, "there's a direct correlation between how people treat themselves and their pets," he said.

That could be the downfall for Cincinnati's dogs, because one-third of us humans are overweight. And just as with people, extra weight on pets contributes to diabetes and shortens their life spans - by about 15 percent, or two years for dogs, the survey says.

So what's a handy way to determine if a dog's overweight? "As a general rule, you should be able to feel your pet's ribs but not see them," said Gitz.